Anybody know,what type of chemical reaction will takesplace if lubricant get mixed with diesel fuel other than a decrease in viscosity and flash point or how diesel can alter the lubricant properties.Requesting your valuable replies.

1. Decresed viscosity is the consecuence of the hidrocarbon chains structure modification. Diesel is a diferent "weight" hydrocarbon.
2. Diesel can contain diferent aditives (i.e. sulfur) that reacts with lubricants chemistry
3. Normally I will expect Diesel dirtier than lube oils
4. I am asumming that the diesel origin is from the combustion chamber. If this is the case H2SO4, a lot of carbon (soot) and water will also be added to the oil

Thank you Mr.Luis Velasco

Many of my lab result shows a reduction in both TBN and TAN in such dilution cases.A reduction in TBN is understandable.But the reduction in TAN is something abnormal.Does it mean that the diesel has an adverse effect on TAN value.

In the described case (mixing diesel fuel with oil), it is quite understandable and expectable that both TBN and TAN would drop. It is a simple neutralization reaction (basic reactions in chemistry). Bases that form TBN react with acids that constitute TAN. As a result both TBN and TAN are lowered.

Krishnakumar,
This mix is made with "crude" diesel or combustion sub products?

If this is the case as described by Mr John Micetic,why the above drop of both TBN and TAN observed in dilution cases only.

In normal cases the TBN has droped and TAN increased.

The above mix is made with the combustion products only and not with crude diesel.

Krishnakumar,

TAN in Engine oil is due to additives.Fuel dilution rapidly depleates additives resulting
in reduced TAN level.

Regards

Bala.

Thanks Mr.Bala and thanks for others also.

Fuel dilution cases are a matter of concern in my area.Customers are not satisfied with an oil analysis report,They want to know an approximate % of the fuel dilution.How can I get a fuel dilution chart to solve these type of problems.Please help me in this regard.

Regards,
MENON.

MEON.

If you know the oil's visc at 40°c and 100°c
(And the fuels visc at 40 and 100°c) you can use the viscosity index for blended oils. (Or other temperatures in F or C)

On diesel engine oils, we first take flashpoint at 186°c. If positive, we use a FuelSniffer witch measures up to 10%. Then if the visc is way off compared to new oil, it is possible to estimate a more acurate % by the link under. (If the oil is not contaminated with other fluid than fuel)

http://www.shellglobalsolutions.com/base_oils/toolbox/toolbox.htm

My oil analysis reports (about 80 per month)always come back with a fuel dilution %. I do not believe in the old tale of not worrying if it is under 2%. I address all dilution and it's possible causes with my clients, and with those who listen, we've gotten it down to almost never. I have some posted on my website www.widman.biz (will be adding more in the near future). I have seen 25%, and in one case I didn't even bother to send a sample to the lab as we drained 25 liters out of an engine with a 12 liter oil capacity.

Menon,

Why do you want to live with "fuel dilution?" Better option is to find the root cause and then arrive at a solution.

Hussam Adeni

Dear Mr.Hussam Adeni,
Thanks for your comments.I am talking about mining area.In this area the dumper drivers are not taking much care on operating the engines.They even leave the dumper without stoping the engine for long time.This excessive ideling causes fuel dilution.Most of the fuel dilution cases are due to this problem.There are about 2000 - 3000 cummins engines are distributed in this area.From all these engines samples are drawn after 250 - 300hrs of operation.All the sample analysis results shows a reduction in Kv both @ 100 and 40°c,followed by a drop in FP.No injector dribling and no mechanical failure.The only reason is excessive ideling.That is why we are concern over the issue.

Menon,

You seem to have got to the root of the problem. Long idling periods. To treat, this the next step is to coax the workshop guys to alter the air-fuel ratio ( on a few selected HEM's) such that idling without raising will stop engine. A fine balance is required but worth a try.

Analyse results and implement appropriately.


Hussam Adeni

Dear Mr Menon,

I don't know whether you have already solved the problem. I have just read your problem and answers given by other. Through FT-IR we can quantify diesel dilution. In an used lube oil, where there is no diesel dilution, different concentrations of diesel (0.5% to 3%) are mixed and take the FT-IR spectra for each of these samples. Diesel dilution is detected at 800-820 cm-1. Calculate the area under the curve and make a calibration curve ( area vs concemtration of diesel). Compare this with a sample having unknown diesel content. I have seen it works.

Kind regards,


dEbasish - SOS Lab

Dear Mr Menon,

You can find out the % of fuel in lube oil in the following way:
Take 1% to 4% fuel in lube oil at varying concentrations, 1, 1.5, 2, 2.5 etc. Take FT-IR and generate a graph conc. vs. area under the curve at 800-820 cm-1. Now, take the unknown sample and see at which point of the graph this unknown conc. falls. Then you can calculate its conc. in the lube oil.

Regards,


Debasish Mukherjee - SOS Lab, TIL, Kolkata, India

I think viscosity drop or loss of film strength due to the dilution would be of primary concern. Secondary concern is the affect on the additive package. I'm of the mindset that there is not a lot of value in being concerned of how the additive package is affected if there is a known/active fuel dilution problem going on. It would be better to correct the problem/cause(s) and make changes to prevent reoccurrence.

Regarding detection, I would agree with previous posts that waiting for a >2% indication of Fuel Dilution by FTIR is not a great approach if you are serious about trending the ingression rate. I would recommend using Gas Chromatography (ASTM 3524 modified) to detect and trend fuel dilution if the need exists to monitor below 2%. We have used G.C. for fuel dilution monitoring to .01% on emergency diesel generator crankcase oil with good results.

Part of the problem with monitoring for fuel dilution using FTIR is dependant on the sample frequency of the engine and the quality of the sample. If the sample frequency is too long, it is likely an active fuel dilution problem can manifest itself into a big problem before the next sample. This very real if the last reading was "just below" detectable with FTIR (2%), and the next sample is 6 months or a year later, and a worst case the problem gets worse with time.

It might not be financially practical to analyze all of the fleet engines with specialized tests, such as G.C. Perhaps, make a selection of a handful of the best and worst and concentrate on these to figure out the best solution to fix the problem. Don't forget about the walkdown of the equipment and check oil supplies, filters, and breathers.

Good Luck.